1. Field of the Invention
This invention relates generally to servo systems for controlling the attitude of a controllable receiver antenna and more particularly to binary digital logic circuitry for providing the appropriate drive signals to the antenna drive motors for slewing the antenna to a remote signal source which makes relatively small excursions about a fixed reference point.
2. Description of the Prior Art
When a synchronous satellite is in orbit, it is substantially positioned over the same predetermined point on the earth with slight temporary nutation or excursions away from this point occuring as a function of time due to orbital mechanics. In order to properly utilize communications signals originating in the satellite and transmitted to a ground station, it becomes necessary to track the satellite as it makes its excursions. Servo systems for controlling the attitude of an antenna are well known to those skilled in the art. Additionally, systems such as step-track scanners have been utilized to accomplish the task of pointing an antenna to a synchronous satellite; however, such apparatus has proved to be extremely costly and exhibits relatively slow reaction time to satellite movement.